The invention relates to a microsurgical microscope system with a stand and with a microscope arranged thereon, in which system the stand has a base part and a substantially horizontal parallelogram linkage with two substantially horizontal bars and first and second further bars connecting the horizontal bars, of which the first further bar is connected to a mounting device for the microscope.
For operations on fine biological structures, in particular for neurosurgical operations on the brain and spinal cord, but also in the ENT field, operating microscopes are used which are arranged on easily movable stands near the operating site.
Depending on the type of operation, operating microscopes and stands of different size and design are used. In neurosurgery, systems have proven particularly useful in which the stand has weights which, in the manner of a balance, compensate the weight of the operating microscope. However, since the microscope has to be moved in the three spatial directions, the stand must have at least three axes of movement. While one axis can be arranged vertically and for this reason no weight compensation has to take place around this axis, it is necessary to effect the balance about two axes by changing the weights or moving the weights.
A great many examples of such stands can be found in the patent literature. In particular, U.S. Pat. No. 5,528,417 describes a system in which the microscope weight is compensated by a counterweight which is moved along a curve depending on the weight of the microscope. In this system, the holder for the microscope is additionally held horizontally by connecting bars, so that the microscope is always suspended vertically under the holder.
Depending on the operation, different additional parts are needed on the operating microscope, and these alter the weight of the operating microscope. For this reason, the system has to be balanced again after the microscope has been re-equipped.
However, regularly required weight compensation has disadvantages. For compensating the shift in weight, the range of compensation is limited and has to be widened by arranging additional weights on the stand, if necessary. In the case of automatic balancing, a high level of electromechanical expenditure is necessary, which considerably increases the costs of a system. If it is forgotten to carry out the balancing procedure, the result is inconvenience for the surgeon or even a danger to the patient through uncontrolled movements of the microscope.
For these reasons, the microscopes are equipped with all possible accessory parts, even if these are not required for an operation. In this way it is possible to dispense with a balancing procedure before the operation and thus avoid the associated risk of imbalance. The disadvantage, however, is that the microscope is made large and unwieldy by the many accessory parts and greatly obstructs the view of the operating site.
The invention starts out from a microscope system of the type mentioned in the introduction (U.S. Pat. No. 5,528,417). The object of the invention is to make available a microscope system in which accessory parts can be arranged on and removed from the microscope without the need for renewed balancing.
The solution according to the invention lies in the fact that the first further bar also has a receiving device connected to it for accessory parts of the microscope and/or additional weights.
The invention makes use of the knowledge that in this microscope system the balancing does not change if the weight acting on the parallelogram linkage does not change. This weight does not change, however, if parts of the microscope, which is connected to the first further bar of the parallelogram linkage, are removed and are arranged in or on the receiving device for the accessory parts, which is likewise connected to the first further bar of the parallelogram linkage. The fact that the distance of these objects from other parts of the stand or any of the hinges of the parallelogram linkage changes, which change would cause different rotational moments, surprisingly is not important here. This is due to the fact that, even upon swiveling of the parallelogram linkage, the orientation of the first further bar of the parallelogram linkage and of the microscope and accessory parts arranged thereon does not change.
Accessory parts which are not required at a given time do not therefore impede the work with the microscope because they can be removed from the microscope and can be arranged in or on the receiving device for accessory parts, where they no longer obstruct the work with the microscope. The corresponding parts do not have to be carried through the operating theatre and in particular taken to other rooms, which would entail the risk of these parts being damaged, mislaid or contaminated. A new balancing procedure after exchange of an accessory part is not necessary. Instead, the balancing procedure can be carried out once for a defined microscope and for a defined set of accessory parts. No automatic balancing devices of any kind are required any longer. In this way, the stand as a whole can be made lighter, smaller and less expensive.
In some circumstances, the accessory parts for the microscope take up a relatively large amount of space, so that it can be difficult to accommodate them at the end of the parallelogram linkage in the receiving device. In this case, a receiving device for accessory parts of the microscope and for additional weights can be provided on the base part. For each accessory part in this case, an equally heavy additional weight is provided which, if it is made of solid metal for example, obviously takes up a much smaller volume than the accessory part. If the relatively large-volume accessory part is not needed, it can be accommodated in the receiving device on the base part, where there is sufficient space. In its place, the substantially smaller additional weight is then arranged in the receiving device at the outer end of the parallelogram linkage near the microscope.
The invention can be used on all stands in which the microscope is arranged on a substantially horizontal parallelogram linkage. xe2x80x9cSubstantially horizontalxe2x80x9d is intended to signify only that the stand part in question is not a substantially vertical stand part, which is more or less vertical above a foot part, for example, but instead an arm which extends to the side of the foot part or base part and at whose end the microscope is arranged. The parallelogram arm could for example be arranged on a vertical column or on a horizontal double-hinge arm which permits coverage of the XY horizontal surface.
A particularly advantageous microscope system in which the parallelogram linkage forms a first parallelogram linkage is characterized in that the stand also has:
a second substantially vertical parallelogram linkage with two substantially vertical bars and two substantially horizontal bars, of which one of the substantially vertical bars is mounted on the base part so as to be able to pivot about a pivot axle,
a third substantially vertical parallelogram linkage whose first lower hinge on the pivot axle of one of the substantially vertical bars of the second parallelogram linkage is connected to the base part, and whose second lower hinge is likewise connected to the base part and is connected via its upper bar to the first parallelogram linkage,
where a substantially horizontal bar of the first parallelogram linkage is a continuation of the upper substantially horizontal bar of the second parallelogram linkage,
where the second lower hinge of the third parallelogram linkage is arranged higher than the first, the connection line between first and second hinge forms with the horizontal an angle of approximately 30xc2x0 to 60xc2x0, and the upper bar of the third parallelogram linkage forms the second further bar of the first parallelogram linkage.
In the already known microscope system, the first parallelogram linkage and the third parallelogram linkage are connected via a lever with two branches which between them enclose an angle of 90xc2x0. The lower branch is always held horizontal, and the upper branch is always held vertical. This provides a very great range of pivoting for the first parallelogram linkage and consequently for the microscope arranged thereon. However, in the normal position, when the first parallelogram forms a rectangle, said first parallelogram is horizontal, with the result that the operating surgeon can strike his head on it. For this reason, in the prior art, it is necessary for the substantially horizontal bars to be arranged high up or for them to have a curvature away from the operating site. In the microscope system according to the invention, this is not necessary if provision is made that the second lower hinge of the third parallelogram linkage is arranged higher than the first, and that the connection line between the first and second hinges forms with the horizontal an angle of approximately 30xc2x0 to 60xc2x0, and that the upper bar of the third parallelogram linkage forms the second further bar of the first parallelogram linkage.
In this case, that bar of the first parallelogram linkage which is situated near the second and third parallelogram linkages is not vertical, but instead at an angle of approximately 30xc2x0 to 60xc2x0, preferably 45xc2x0, so that in this normal position the first parallelogram linkage is directed obliquely upwards and the operating surgeon has room to stand below it.
After all the necessary accessory parts and the corresponding additional weights are arranged in the receiving device on the first parallelogram linkage or on the microscope, this microscope system can be equilibrated. This is expediently done by weights which can be arranged on the parallelogram linkages, in particular on the second parallelogram linkage. This balancing can be carried out once by a technician or by a theatre nurse for a given system, and it can be retained as long as the additional devices for the microscope are not replaced by others.
Electrically or pneumatically releasable brakes are expediently arranged on hinges and/or the pivot axle. These brakes are released only if the stand is to be adjusted, that is to say if the microscope is to be moved to another position.
A particularly expedient configuration is characterized in that the bars of the parallelogram linkages are pipes which are held in bushings which form parts of the hinges and/or of the pivot axle. The hinge axles and/or the pivot axle can be arranged in the bushings outside the longitudinal axis of the pipes. To create more space for the operating surgeon, at least one bar of the parallelogram linkage can be curved in the direction away from the operating site.
The base part will expediently rest on the floor and can be provided in a manner known per se with lockable castors. However, it could also be arranged, for example, on the wall or on the ceiling of the operating theatre. The base part expediently has a foot part and a column which is pivotable about a vertical axle and on which the further parts of the stand are then arranged.
However, the main feature of the invention is that, when the stand is swiveled, the angle at which the microscope and the receiving device for the accessory parts are oriented does not change. If the total weight of the microscope and of the accessory parts which are arranged on the microscope or on/in the receiving device does not change, the balance is maintained.